Wellhead seal



Aug. 21, 1962 K. w. FOSTER ET AL 3,050,127

WELLHEAD SEAL Filed July 30, 1959 4 32 .47 46 30 ,4 ll 3 3| ZR M 50 l4 13 I2 X56 58 20 2| "2) h f} FIG.| l

INVENTORS:

54 K. w. FOSTER N. B. NEWMAN 25 24 R. GEER 53 BY: N71 0? FIG. 2

THEIR AGENT United States Patent 3,050,127 WELLHEAD SEAL Kenneth W. Foster, Nicholas B. Newman, and Ronald L. Gear, Houston, Tex., assignors to Shell Oil Company, a corporation of Delaware Filed July 30, 1959, Ser. No. 830,504 4 Claims. (Cl. 166-97) The apparatus relates to equipment used on oil wells, and pertains more particularly to a wellhead seal adapted to close the open top of a wellhead closure apparatus of the type described in copending patent application, Serial No. 830,587, filed July 30, 1959.

The present invention is particularly concerned with a wellhead seal for use in closing the wellhead assembly positioned under water where equipment is subject to the corrosive action of sea water as well as to the accumulation of various types of marine growth on the equipment after prolonged exposure to sea water. A copending application, Serial No. 830,587, filed July 30, 1959, and entitled Underwater Well Completion Method, describes a method for drilling and completing wells under water at an offshore location by the use of a marine conductor tube, extending from the surface of the water to the wellhead, through which drilling and completion operations are carried out from a remote operational station positioned on or above the surface of the water. After installing the wellhead equipment on a completed well, the top of the wellhead assembly is closed in a suitable manner, such as by means of a lubricator, or wellhead closure apparatus as described in copending patent application, Serial No. 830,587, filed July 30, 1959. In turn, the lubricator or wellhead closure may be closed by means of a wellhead seal in accordance with the present invention.

It is desirable to close underwater wells in a manner such that all possibility of any corrosion of the equipment is eliminated. One suitable method of accomplishing this is to inject a material, such as an oil or grease, into voids in a wellhead assembly as well as between all metal parts which may be disconnected or moved at a later date. The protective material used is preferably a fairly viscous material to which have been added one or more materials such as agents which inhibit the corrosion of metals, the growth of marine life, etc.

It is therefore an object of the present invention to provide an apparatus which may be readily employed to force a lubricating material, such as a grease, into the voids of a wellhead assembly.

A further object of the present invention is to provide apparatus adapted to form a fluidtight seal at the top of a wellhead assembly, or a related closure member.

Another object of the present invention is to provide a wellhead seal of rugged design and construction which is not readily injured by the rough handling encountered during the completion of a well at an offshore location.

A further object of the present invention is to provide a pneumaticallyor hydraulically-operated wellhead seal adapted to be installed in or removed from a wellhead assembly from a remote location.

These and other objects of the invention will be understood from the following description taken with regard to the drawing wherein:

FIGURE 1 is a view taken partially in longitudinal cross-section of the wellhead seal of the present invention illustrated as being seated in the open top of a wellhead apparatus; and,

FIGURE 2 is a view taken partially in longitudinal cross-section of a running tool for inserting the wellhead seal of the present invention into place in the top of wellhead apparatus.

Referring to FIGURE 1 of the drawing, the top of a member 23.

wellhead enclosure apparatus 11, which has vertical conduits 12 and 13 therein, is shown as having a recessed portion 14 in the top thereof for accommodating the wellhead seal of the present invention. Slidably mounted on the outside of the wellhead closure apparatus 11 is a ring-like member 15 secured to the top of a bellows unit 16. Both the ring member 15 and bellows unit 16 are adapted to be forced downwardly by suitable well equipment when it is desired to re-establish contact with a well with equipment for work-over operations conducted from the surface of the water. However, normally the ring member 15 and bellows unit 16 are in the position shown when the wellhead is closed. At this time the space 17 between the bellows unit 16 and the outer surface of the wellhead closure apparatus 11 is filled with a preferably viscous material to which corrosion inhibitors, marine growth inhibitors, etc., have preferably been added. In a preferred embodiment of the present inven tion, a grease including these inhibitors is forced down through vertical conduits 12 and 13 and out through small lubrication injection ports 20 and 21 which are in communication between the vertical conduits 12 and 13 in the space outside the wellhead closure apparatus 11 as described in copending patent application, Serial No. 830,587, filed July 30, 1959.

The wellhead seal of the present invention comprises a hollow cylindrical body member 23 having a chamber 24 formed therein. A guide rod 25 is coaxially disposed within the cylindrical body member 23 with the upper end of the guide rod extending through the top 26 of a cylindrical body member 23 in sliding engagement therewith. The top of the guide rod 25 is provided with fishing neck 27 by which the Wellhead seal of the present invention may be withdrawn upwardly to the surface of the water by any suitable type of retrieving apparatus well known to the art, such for example, as by a wireline fishing device (not shown).

The lower end of the guide rod 25 is provided with a flange 30 which normally seats against the inside face of the bottom 31 of the cylindrical body member 23. If desired, a guide post 32 may be fixedly secured at its lower end to the bottom plate 31 of the body member 25, with a cylindrical recess 33 formed in the lower end of the guide rod 25 to contain the guide post 32. A piston 34 is slidably mounted within the chamber 24 of the cylindrical body member 23.

Thus, the piston 34 is slidable within the chamber 24 while the guide rod 25 in turn is slidable through the piston and through the top plate of the cylindrical body The upward travel of guide rod 25 is limited by the flange 30 when it contacts the under surface of the piston 34. The present wellhead seal is pro vided with conduit means in communication between opposite sides of the piston 34 for bleeding fluid from one side of the piston to the other. A preferred form of this conduit means, which is preferably closed when the piston is in the position illustrated, comprises one or more ports 35 through the guide rod 25 in communication between the cylindrical recess 33 therein and the space outside the guide rod 25. The ports 35 are placed near the top of the cylindrical recess 33 in a manner such that when the guide rod 25 is withdrawn upwardly so that the port 35 is above the upper surface of the piston 34, a fluid within the chamber 24 above the piston 34 may bleed through the port 35, down through the cylindrical recess 33, out into the space below the piston 34, and thence downwardly through one or more discharge ports in the bottom plate 31 of the cylindrical body member 23. In the event that the chamber 24 of the cylindrical body member 23 is to be filled with a more viscous liquid, the conduit means between opposite sides of the piston 34 may comprise one or more small diameter ports 37.

The top plate 26 of the cylindrical body member 23 is provided with one or more ports 40 and 41 normally closed by spring-loaded check valves 42 and 43 whereby a fluid may be pumped into the chamber 24 of the body member 23. Spring-loaded latch means, such for example, as a plurality of locking elements 44, are pivotally secured to the cylindrical body member 23, as at 45. The lock ing elements 44 are all connected to suitable spring means, such for example, as a circular tension spring 46 which is adapted to Withdraw the locking elements 44 to their inoperative position within the chamber 24 of the cylindrical body member 23 when the piston 34 is withdrawn upwardly above the pivot points 45. As illustrated in FIGURE 1, the locking elements 44 are shown in their operative or looking position as they extend into a recessed groove 47 on the inner wall of the wellhead closure apparatus 11.

The body member is provided with suitable sealing means, such for example, as O-ring seals 50- and 51, for forming a fluidtight seal between the cylindrical body member 23 and the wellhead closure apparatus 11. In general, the cylindrical body member 23 of the present apparatus may be seated within the wellhead closure apparatus 11 with the bottom plate 31 of the body member 23 resting on the bottom of the recessed portion 14 in the top of the well head closure apparatus 11. However, if desired, a seating flange 52 may be mounted on, formed on or secured to the outside of the body member 23 for seating the body member in the top of the wellhead closure apparatus 11.

All portions of the body member 23 which extend above the wellhead closure apparatus 11, and are in contact with sea water during normal placement, are preferably covered with a protective sheath of a non-metallic, preferably soft material, such as rubber, plastic, etc. The protective sheath 53 may have formed on the outer surface thereof one or more outwardly extending flanges 54 which aid in placing the cylindrical body into position. Preferably the flanges 54 are slightly larger in diameter than the diameter of the cylindrical body member 23. Thus, when the cylindrical body member 23 is delivered from an operational base above the surface of the water by pumping it down a marine conductor string, as described in copend ing patent application, Serial No. 830,587, filed July 30, 1959, then the outwardly extending flanges 54 would ride against the inner wall of the conductor pipe. The fishing head 27 is also protected by a covering cap 55 which is made of the same material as the sheath 53.

In FIGURE 2, an apparatus is shown by which a wellhead seal of the present invention may be lowered into place from an operational base above the surface of the water. In this arrangement a cylindrical lowering tool 56 is secured, as by threading, to the lower end of the pipe string 57 through which a ball 58 may be dropped. Mounted for sliding coaxial movement within a downwardly extending cylindrical portion 70* of the cylindrical lowering tool 56 is' a piston element 59 having an open lower end adapted to fit over the fishing neck 27 and its cap 55. The lower end of the downwardly-extending cylindrical portion 70 of the lowering tool 56 has an internal flange element 71 screw-threaded thereto with and upper shoulder 72 of said flange element 71 arranged to cooperate with a mating outer shoulder 73 on the piston 59 when the latter is at the end of its down stroke. The lower end of the cylindrical portion 70 seats on the upper shoulder 74 of an annular piston cap 75 which is provided with a seal 76.

For lowering purposes, the cylindrical body member 23 is provided at its upper end with a cylindrical member 60 which may 'be attached in any suitable manner, as by .screw threads at 61. The cylindrical member 60 is of a size such that the running tool 56 may fit therein, preferably in a fluidtight manner. Connection is made between the piston 59 of the lowering tool 56 and the cylindrical member 60 attached to the top of the body member 23 by means of shear pins 62. In using the lowering tool shown in FIGURE 2, the wellhead seal of the present invention is connected to the lower end thereof by means of shear pin 62 after which the seal is lowered down through a marine conductor pipe string (not shown) until the wellhead seal is seated in its position in the recessed top of the wellhead closure apparatus 11 as shown in FIGURE 1. As this point a ball 58 (FIGURE 2) is dropped down through the pipe string 57 and a pressure fluid is pumped down in back of it. The fluid drives piston 59 downwardly causing pins 62 to shear, thus releasing the lowering tool 56 from the cylindrical member 60. The lowering tool 56 and its elements 70, 71, 75 and its piston 59 and the pipe string 57 may then be withdrawn to the surface. During withdrawal of the running tool 56 upwardly, the shoulder 72 on the tool engages the shoulder 73 of its piston 59 to prevent the piston from dropping out of the tool.

In the event that the arrangement of FIGURE 1 is employed, the piston 34 is raised to the top of the chamber 24 so that a snap ring 63 carried within the recess 64 in a portion of the piston 34 surrounding the guide ring 25, is forced upwardly until it seats in a groove 65 in the guide rod 25. The chamber 24 of the cylindrical body member 23 is then filled with a grease or other lubricating material and pumped down through a marine conductor pipe string (not shown) in back of a quantity of other lubricating or protective fluid containing corrosion inhibitors, marine growth inhibitors, etc., which fluid fills the void within the wellhead assembly. With the wellhead seal seated in place as shown in FIGURE 1, the same or a different fluid is pumped down through the marine conductor pipe string so that it enters ports 40 and 41 and passes down into the chamber 24, forcing the piston 34 downwardly ahead of it. As the piston 34 moves downwardly it forces the locking elements 44 into the recessed groove 47 to securely lock the wellhead seal in place.

When it is desired to withdraw the present seal from the top of the wellhead, a tool may be lowered to puncture or cut away the protective cap '55 covering the fishing neck 27. A fishing tool is then lowered, as for example on a wire line, to engage the fishing neck 27. Upward pull on the fishing neck 27 causes the guide rod 25 to move upwardly until the flange 36 engages the piston 34. The fluid above the piston 34 is then able to drain through the conduit means, either conduit 37 or through port 35 and cylindrical recess 33, into the space below the piston, thus allowing the piston to move upwardly.

When the bottom of the piston has cleared the top of' the locking elements 44, the spring 46 would pull the locking elements out of groove 47, thus unlocking the wellhead seal and allowing it to be removed from the wellhead closure apparatus 11 by continued pull on the fishing neck 27.

We claim as our invention:

1. A remotely positionable and removable wellhead sealing apparatus adapted to close in a fluidtight manner the top of wellhead assembly located under water at an olfshore location, said sealing apparatus comprising a hollow cylindrical body member having a chamber formed therein, said cylindrical body member being of a diameter to fit within the open top of a wellhead assembly having a recessed locking groove on the inner wall thereof, a coaxial rod carried by said body member, the upper end of said rod slidably extending through the top of said body member, a fishing head secured to the extending upper end of said rod, latch means carried by said body member and extendible beyond the outer surface thereof and of a size to seat in the recessed groove on the inner wall of the wellhead assembly, latch actuating means carried by said body member and operatively engaging said latch means, means carried by said body member and operatively connected to said latch means for moving said latch means to a retracted position, and sealing means carried on the outer surface of said body member for establishing a fluidtight seal between said body member and the wellhead assembly.

2. A remotely positionable and removable wellhead sealing apparatus adapted to close in a fluidtight manner the top of wellhead assembly located under water at an offshore location, said sealing apparatus comprising a hollow cylindrical body member having a chamber formed therein and openings through the wall thereof, said cylindrical body member being of a diameter to fit within the open top of a wellhead assembly having a recessed locking groove on the inner wall thereof, a coaxial guide rod mounted within said body member, the upper end of said guide rod slidably extending through the top of said body member, a fishing head secured to the extending upper end of said guide rod, a piston slidably mounted on said guide rod Within the chamber of said body member, inlet port means in the top of said body member for allowing a fluid to enter the chamber thereof, check valve means in said inlet port means, open fluid discharge ports in the bottom of said body member, conduit means in communication between opposite sides of the piston for bleeding a fluid from one side to the other, radiallyextendible latch means carried by said body member and operatively contacting said piston and of a size to extend through the openings in the body member and to seat in the recessed groove on the inner wall of the wellhead assembly, and sealing means carried on the outer surface of said body member for establishing a fiuidtight seal between said body member and the wellhead assembly.

3. A remotely positionable and removable wellhead sealing apparatus adapted to close in a fluidtight manner the top of wellhead assembly located under water at an offshore location, said sealing apparatus comprising a hollow cylindrical body member having a chamber formed therein, said cylindrical body member being of a diameter to fit within the open top of a Wellhead assembly having a recessed locking groove on the inner wall thereof, a coaxial guide rod mounted within said body member, the upper end of said guide rod slidably extending through the top of said body member, a fishing head secured to the extending upper end of said guide rod, a piston slidably mounted on said guide rod within the chamber of said body member, inlet port means in the top of said body member for allowing a fluid to enter the chamber thereof, check valve means in said inlet port means, open fluid discharge ports in the bottom of said body member, conduit means in communication between opposite sides of the piston for bleeding a fluid from one side to the other, a plurality of spring-loaded locking elements carried by said body member near the lower end thereof with a portion of each locking element extending through the openings in the wall of said body for making contact with the piston on one side and for seating in the recessed groove on the inner wall of the wellhead assembly on the other side, spring means operatively connected to said locking elements for urging said locking elements to [a retracted position, sealing means carried on the outer surface of said body member for establishing a fluidtight seal between said body member and the wellhead assembly, and outwardly extending sealing flange on said body member adapted to seat in the open top of said wellhead assembly, and non-metallic sheath means covering at least that portion of the body member and outwardly extending guide rod exposed to sea water when the body member is seated in a wellhead assembly.

4. A remotely positionable and removable wellhead sealing apparatus adapted to close in a fluidtight manner the top of a wellhead assembly located underwater at an offshore location, said sealing apparatus comprising a body member having a chamber formed therein, said body member being of a size to operatively engage the open top of a wellhead assembly having a recessed locking groove in the wall thereof, latch means carried by said body member and extendible lbeyond the outer surface thereof and of a size to seat in the recessed groove in the wall of the wellhead assembly, latch actuating means carried by said body member and operatively engaging said latch means for selectively moving said latch means to an operative position, and sealing means carried on the surface of the body member for establishing a fiuidtight seal between said body member and the Wellhead assembly.

References fitted in the file of this patent UNITED STATES PATENTS 2,478,628 Hansen Aug. 9, 1949 2,581,537 Maisch Jan. 8, 1952 2,605,847 McCoy Aug. 5, 1952 2,757,740 Bohannan et a1. Aug. 7, 1956 patentees was rendered Nov. 6, 1964, as to claim 4.

Notice of Adverse Decision in Interference In Interference N 0. 93,485 involving Patent No. 3,050,127, K. W. Foster, N. B. Newman and R. L. Gear, Wellhead seal, final judgment adverse to the [Ofiicial Gazette December 22, 1964.] 

